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This might have answered my question. I ran a track day (first timer) last weekend in a 2015 C7Z on factory pads/rotors and warped a rotor. I did about 40-50 2.4 mile laps over 5 sessions. I expected the pads to wear out, but I was disappointed about the rotor warp. Next time, I'll try turning off ABS. Any other suggestions to prevent rotor warp? Do ceramic pads help? As far as the actual braking performance, it was fine for me, as a novice, but more would be better there too.
Originally Posted by Johnny C @ OG
IF the brakes went from 100% fine to OMG NOTHING! And then where 100% fine seconds later, then that was a computer trying to kill you. I hate factory ABS systems, And not just because if the ice mode.
ABS,
Factory abs is intended for little old ladies to keep control of the car during a rain storm. Motorsports was never in the ABS meeting at GM. To all of my drivers that bring street cars, I tell them to pull the ABS fuse. It is more headache then solution. The GT-R guys always ignore me but after a few sessions I have miata’s out braking them. Bosch makes the current top level motorsports ABS system. The bosh operates 10 time faster than a OEM abs. it operates so fast there is no sharp change in pressure at the pad. It also works to a %. The Bosh can calculate that at a given moment it will deliver 75% of the supplied line pressure to prevent a wheel locking up. A OEM ABS will detect wheel lock up and goes into a ON-OFF-ON-OFF-ON-OFF-ON-OFF-ON-OFF- program until the wheel slip is gone, or there is no more line pressure. The problem a OEM abs creates is it drastically shortens the life of components. I wouldn’t be surprised if your wheel spinning on the rim was from a factory abs. it also makes your pads life shorter and I have seen brand new (very expensive) rotors crack from it. Imagine getting a rotor up to thermal capacity and then hitting 6x a sec it with iron hammers (pads). for my racers that like the rain put the factory abs on a switch. In the rain the rotors won’t get hot enough to cause trouble.
Like I said, I'm a novice, so I'm looking to learn. I took it to the dealer before the track day and followed must of the track prep (but didn't put the rotor cooling rings on). They wanted $500 to put them on and then take them back off after, and I thought that was nuts.
It would be nice to not warp the rotors every time I run at the track though.
Originally Posted by Johnny C @ OG
wait ceramic...??? what pads where you using? the rotor deformation might be the symptom.
Like I said, I'm a novice, so I'm looking to learn. I took it to the dealer before the track day and followed must of the track prep (but didn't put the rotor cooling rings on). They wanted $500 to put them on and then take them back off after, and I thought that was nuts.
It would be nice to not warp the rotors every time I run at the track though.
that's your problem. Factory pads are built to be quiet. ( i know PFC used to build pads for the mustang). pad noise is the #1 cause of warranty work. so street pads are full of fillers and other stuff to make them quiet. they also have a operating temperature of 0* - 700*. exceed that 700* and pad friction will fall off and rotor temps will skyrocket. think how hot your hands get with a rope getting pulled threw your hands while you try to hold on. I've seen 1800* and fires come from stock pads. Yes they will catch on fire. To fix this we go for a pair of race pads. race pads are built with a higher iron content, along with other tings. most race pads can take 1400*-1600* before the friction falls off. using a set a squeaky race pads will keep rotor temps down and it will slow deformation. shoot me over a PM with what tires your using along with what year your car is and i'll recommend a good set of race pads.
I try to stay out of the ABS while trying to get as close to it kicking in as possible. If it does kick in, I'm able to modulate the brake pedal to disengage it. What I notice is the ABS just hammers the crap out of the rotor. You can see the pad contact points on the rotor afterwards and it contributes to a pulsing pedal. I'll stay away from threshold for a few laps trying to even out the deposits on the rotor but sometimes the high spots won't go away completely until I drive around with cold rotors/race pads.
Thanks for the advice, guys. The pulsing that I am getting is pretty fast paced and doesn't happen at high speed, but it stops pretty rough at low speed when coming to a complete stop. That said, it doesn't have the slow, exaggerated, jerkiness that I've seen with warped rotors before. Is it possible the pulsing is just being caused by my fried pads? They all seem to have plenty of pad left, but look ragged on the contact surfaces. I don't see anything visually wrong with the rotors - is there a way to tell which or rotor/pad is bad?
Thanks for the advice, guys. The pulsing that I am getting is pretty fast paced and doesn't happen at high speed, but it stops pretty rough at low speed when coming to a complete stop. That said, it doesn't have the slow, exaggerated, jerkiness that I've seen with warped rotors before. Is it possible the pulsing is just being caused by my fried pads? They all seem to have plenty of pad left, but look ragged on the contact surfaces. I don't see anything visually wrong with the rotors - is there a way to tell which or rotor/pad is bad?
Take the wheel off and spin the rotor by hand. If it is warped, you will feel some resistance in the spot where it is warped while it flows freely where it is not.
I've warped pads running warped rotors before. To check, you have to remove the pads. Run your fingers along the pad. If it's warped you will feel it.
Here are photos and background:
C5Z stock power and brakes and run Toyo R888. I have the DRM and Lambert ducts going to the front brakes. I use centric blanks, usually the cryro versions and Raybestos ST43 pads. I normally would get 5 or 6 track days on the rotors. I cracked 2 fronts and 1 rear rotor in less than two days in October. The Genesis paint I put on the outer edge and in the veins of the rotor turns yellow. (1075 -1326F). Lots of longitudinal taper. Radial is not bad. Long Pedal but the car stops fine. I despise the long pedal!
Thoughts?
Front Driver
Front passenger
Rear
Typical C5 brake issues. The calipers taper the pads like that when the cars are brand new and the rotors will crack if you use any track level type of brake pad. When I took delivery of my 97 there were only street pads available for the first few years and I would go through a set of pads at every two day event (flipped pads from one side of car to the other to even out the taper) and the rotors lasted for several years. Then as I was able to purchase PFC track pads the rotors started cracking every two to three days. Cheap ones were no worse than expensive ones so I went with the cheap NAPA Ultra Premiums at $25 ea. PFC pads would last 5 or 6 days and they still tapered. The pedal would get so long I couldn't heel toe properly since the brake pedal was almost to the floor. I had to start tapping the brake with my left foot as I approached a braking zone so the pedal was high enough. Suffered through this for 5 years from 2000 to 2005 when I went to the LG G Stop kit on my 03Z. Those pads still tapered but because the calipers were fixed instead of floating the taper didn't cause a long pedal. Never resolved the rotor cracking problem. They just weren't big enough for the heat being generated. I had several crack in two places at a time and some of them had cracks all the way through so you could see through the rotor. They would crack in the paddock or on the track so spending time cooling them off after a session didn't help much.
The only solution on a C5 is a BBK with larger rotors and changing the duct work so you get much more cooling air. One forum member even went to the bother of adding plastic pipe and scoops under his car to route cooling air to both the front and rear rotors. I think I still have copies of the pictures he posted on the forum about 15 years ago.
There is a side benefit to all of the cracked rotors, they are worth some money as scrap. A year or so before I moved to Charlotte I emptied my shed of all of the cracked and about to crack C5 rotors and took them to the junk yard. A total of 500+ pounds of cast iron and I got $75 for it although it cost me $12 in gas to get there and back.
I rarely got into the ABS when on track. That usually happened when I got into some fluid or other material that reduced grip so I am pretty sure the rotor cracking was just due to excessive heat and too small of a rotor.
Bill
Last edited by Bill Dearborn; 11-25-2015 at 02:40 PM.
Thanks for the advice, guys. The pulsing that I am getting is pretty fast paced and doesn't happen at high speed, but it stops pretty rough at low speed when coming to a complete stop. That said, it doesn't have the slow, exaggerated, jerkiness that I've seen with warped rotors before. Is it possible the pulsing is just being caused by my fried pads? They all seem to have plenty of pad left, but look ragged on the contact surfaces. I don't see anything visually wrong with the rotors - is there a way to tell which or rotor/pad is bad?
The first weekend I had the C7Z I took it to the track on stock pads. It did ok but I was still learning the car and was a bit timid. Next event at VIR I could go 2-3 laps before the stock pads overheated and I'd have to back off. However, I've never had anything like warped rotors.
Is it possible this is just inconsistent pad material on the rotor? I've had that problem with track pads on my old car. If even the stock pads hadn't been properly bedded that could happen.
If you want to try and fix it get some of those scotchbrite pads you can stick on a drill and a couple cans of Brakleen. host the rotors down and scrub them with the scotchbrite to try and remove the pad material. That's worked for me before but YMMV.
The first weekend I had the C7Z I took it to the track on stock pads. It did ok but I was still learning the car and was a bit timid. Next event at VIR I could go 2-3 laps before the stock pads overheated and I'd have to back off. However, I've never had anything like warped rotors.
Is it possible this is just inconsistent pad material on the rotor? I've had that problem with track pads on my old car. If even the stock pads hadn't been properly bedded that could happen.
If you want to try and fix it get some of those scotchbrite pads you can stick on a drill and a couple cans of Brakleen. host the rotors down and scrub them with the scotchbrite to try and remove the pad material. That's worked for me before but YMMV.
i have worked with every kind of brake system, i've worked with everything like police fleets, spec miata teams, chip ganassis DP tea, i mean everything. i've sold $5,000,000 worth of brakes in 2012 alone. i have yet to see a rotor be warped. it doesn't happen. 9 times out 10 the pulsation is Lateral run out.
most of the time it's caused from a damaged hub, an other likely candidate is a Dirty or rusty hub (that won't let the rotor sit flat on the hub), 10% of the time it's build up of pad material. if you do have lateral run out, the rotor is toast and need to be replaced.
I've had mechanics call me an idiot and try to prove me wrong, but every time i find the cause and it's never that the rotor just warped.
I don't have nearly the experience Johnny C has, I've found with pulsing brake pedal issues, the cause is brake pad deposite buildup on the rotor. I use 130 grit sand paper to remove it, then thoroughly blow it off with compressed air. Dome claim the rotors are warped, but I've never seen it.
I don't have nearly the experience Johnny C has, I've found with pulsing brake pedal issues, the cause is brake pad deposite buildup on the rotor. I use 130 grit sand paper to remove it, then thoroughly blow it off with compressed air. Dome claim the rotors are warped, but I've never seen it.
yea the most of the time it's an install error.
short story, i had one shop (police) call me and said my rotors where defective. i did some research and found the mechanic was greasing the mating surface of the rotor and hubs. His grease gun would pick up stones off the floor and the grease would hold the tiny rocks. once installed the rotors never spun true. that was a $5,000 mistake on part of the mechanic. i told them not to grease the hubs, and to clean the hubs with wd40 and a small wire brush to remove surface rust. all the pulsations went away.
yea the most of the time it's an install error.
short story, i had one shop (police) call me and said my rotors where defective. i did some research and found the mechanic was greasing the mating surface of the rotor and hubs. His grease gun would pick up stones off the floor and the grease would hold the tiny rocks. once installed the rotors never spun true. that was a $5,000 mistake on part of the mechanic. i told them not to grease the hubs, and to clean the hubs with wd40 and a small wire brush to remove surface rust. all the pulsations went away.
That is a very interesting story. He probably had trouble getting a rotor off a hub one time & figured he'd "grease em up good" so it never happened again.
I didn't read the whole post, but I do have a question.
I am new to the C5 Z06, I now have a total of 4 weekends on the car(8 days). I have been on crap tires learning the car.
Pads are Raybestos ST47/ST43. I am still on the same set of fronts and have burned up 2 seats of rears, all traction control is OFF.
What is the deal here?
TMTRAYLOR-
On the cracked stock rotors, take the cooling ducts off the car and run it for a test. I learned with Wilwood rotors you can have too much cooling which heat cycles the metal. Put temp strips on the caliper. I have 4 days on my rotors with no cooling ducts, they show stress cracks but nothing abnormal. My temp strips show 400* on the caliper.
You want heat in the rotor and you want to keep it. The big temp swings stress the metal of the rotor.
I have also seen rotors being cracked by not enough cool down(I think this is what's happening in this case), I always come off track and ride the paddock or entry road for extra cool down. When you stop moving the cooling air stops, I have heard many a rotor go *PING* in the paddock because of a lack of cool down.
On the long pedal, better brake fluid and check the wheels bearings. Doesn't take much wheel bearing play to cause a long pedal.
Last edited by FASTFATBOY; 11-28-2015 at 07:40 AM.
My question is quite similar. I have a C5Z with stock calipers front and rear with moderately effective cooling ducts to the fronts.
Personally I am pretty happy with the Raybestos ST43s up front as far as pad taper and wear is concerned and am not likely to get a BBK as the car is dual purpose Z16 car and sometimes needs to look pretty with stock 17" front rims.( I compete in Time-Attack on a square 18 x 10.5 set up). I usually use good street tires, (Rivals and similar) or Nt01s so no slicks or Hoosiers here.
Interestingly, after a 1-2 lap cool down, brake temps are about the same front and rear although obviously the front has hotter temps during competition and has had the advantage of 2 laps worth of cooling duct action.
My question is, given that the rears are likely cooler than the fronts, what is an appropriate temp range stagger. I totally appreciate what was mentioned earlier in this post that initial bite is not necessarily a great thing if it leads to poor modulation but most higher temp pads seem to have higher initial bite. Some folks seem to run the same pad front and rear but I would have thought the cooler rear temps would require a different pad.
Does anyone have temp readings front to rear on a similar setup?
DO NOT LISTEN TO WILLWOOD REPS. Wildwood contracts out it’s reps. Meaning that they will pay a random salesmen to pitch their products. Those people are not “in the office” of willwood. They do not have access to vital training. they are just guessing. they are grasping at straws to make a sale. this misinformation can kill you!
Rotor temps. The temperature of your rotor is a byproduct. I say that because it varies on many things like vehicle weight, driver, pad compound, brake bias, driving style, horsepower, ambient air temperature, driving style, tires compound, tire size. Yes I mentioned driver 3 time because he can affect the rotor temp more than anything else. Because it has so many variables just remove it from your calculations. There is no perfect rotor temp. when I’m in the pits I’ll use a probe and record rotor temps. The only thing I’m looking for is a spike. If I see 100* difference from right to left I know I have drag in the system.
Overcooling your brakes, doesn’t happen. Everyone is amazed at how slow it takes to cool a rotor with one 3” hose. Hell I’ve seen 5x 3” hoses and it still took a long time to dissipate the rotor’s heat. The only time you should tape your cooling ducts is when you’re looking for less drag, or it’s raining.
The reason corvette rotor’s crack is in the engineering of the rotors. Similar to the S2000 rotor. When the rotor starts to thermally expand it is restricted by the hat. That “cooler” center piece of iron is in essence giving the rotor its own thermal shock. That’s why cracks that protrude into the hat are fairly normal. The fix isn’t to remove your cooling ducts but to find a better engineered rotor. A AP j hook or a PFC two piece rotor will fix that issue. The outer rings are replaceable and it can save you a few hundred over a season. http://www.ogracing.com/performance-...corvette-c5-c6 you can get these at KNS, & Vengeance Road Racing. Sight sponsors
11-23-2015, 05:50 PM
